Amid warnings that high housing prices and snarled freeways are driving off some manufacturing companies, demand for factory space in Orange County grew more than 15% in the first nine months of the year.

But that wasn't enough to whittle down a vacancy rate of 14%--or 21 million square feet of empty space--in the third quarter, according to a recent survey by real estate firm Coldwell Banker.

In contrast, the national vacancy rate for industrial space was a much lower 5.8% in July, August and September and was only 6.6% in Southern California for the period, according to Coldwell Banker.

Most in Irvine

Much of the construction of industrial buildings during the third quarter was in Irvine, which has a sizable amount of raw land zoned for industrial use.

But Cypress, just west of Anaheim, was home to a building boom that will triple the amount of industrial space there, according to the survey. Many of the Cypress construction sites were formerly farmland, said Scott Perley, a Coldwell Banker vice president in Santa Ana.

So hectic has industrial construction been in Irvine that it has outpaced Anaheim as the county's leader in total factory space.

Anaheim, once the biggest industrial center in the county, doesn't appeal as much to the new computer and biomedical companies that make up a large portion of Orange County's new industries, Perley said.

"In the north county there are a lot of smaller, individual land parcels," he said, "and your neighbors might not necessarily have a pretty building."